Provided by: ifupdown_0.7.54ubuntu1_i386 bug

NAME

       /etc/network/interfaces  - network interface configuration for ifup and
       ifdown

DESCRIPTION

       /etc/network/interfaces  contains   network   interface   configuration
       information  for the ifup(8) and ifdown(8) commands.  This is where you
       configure how your system is connected to the network.

       Lines starting with `#' are ignored. Note that end-of-line comments are
       NOT supported, comments must be on a line of their own.

       A  line  may  be  extended  across  multiple  lines  by making the last
       character a backslash.

       The file consists of zero or more "iface", "mapping", "auto", "allow-",
       "source" and "source-directory" stanzas. Here is an example.
       auto eth0
       allow-hotplug eth1

       source interfaces.d/machine-dependent

       source-directory interfaces.d

       mapping eth0
            script /usr/local/sbin/map-scheme
            map HOME eth0-home
            map WORK eth0-work

       iface eth0-home inet static
            address 192.168.1.1
            netmask 255.255.255.0
            up flush-mail

       iface eth0-work inet dhcp

       iface eth1 inet dhcp
       Lines  beginning with the word "auto" are used to identify the physical
       interfaces to be brought up when ifup is run with the -a option.  (This
       option  is  used by the system boot scripts.)  Physical interface names
       should follow the word "auto" on the same line.  There can be  multiple
       "auto"  stanzas.   ifup  brings  the  named  interfaces up in the order
       listed.

       Lines beginning with "allow-" are  used  to  identify  interfaces  that
       should  be  brought  up automatically by various subsytems. This may be
       done using a command such as "ifup --allow=hotplug  eth0  eth1",  which
       will  only  bring up eth0 or eth1 if it is listed in an "allow-hotplug"
       line. Note that "allow-auto" and "auto" are synonyms.

       Lines beginning with "source" are used to include  stanzas  from  other
       files, so configuration can be split into many files. The word "source"
       is followed by the path of file to be sourced. Shell wildcards  can  be
       used.  (See wordexp(3) for details.)

       Similarly,  "source-directory" keyword is used to source multiple files
       at once, without specifying them individually  or  using  shell  globs.
       Additionally,  when  "source-directory" is used, names of the files are
       checked to match the following regular expression: ^[a-zA-Z0-9_-]+$. In
       other words, the names must consist entirely of ASCII upper- and lower-
       case letters, ASCII digits, ASCII underscores, and ASCII minus-hyphens.
       In the directory path, shell wildcards may be used as well.

       When  sourcing  files  or directories, if a path doesn't have a leading
       slash, it's considered relative to the directory containing the file in
       which  the  keyword  is  placed.  In  the example above, if the file is
       located at /etc/network/interfaces, paths to  the  included  files  are
       understood to be under /etc/network.

       Currently,  "source-directory"  isn't  supported by network-manager and
       guessnet.

       By default, on a freshly installed Debian system, the  interfaces  file
       includes  a  line  to  source  files  in  the /etc/network/interfaces.d
       directory.

       Stanzas beginning with the word "mapping" are used to determine  how  a
       logical interface name is chosen for a physical interface that is to be
       brought up.  The first line of a mapping stanza consists  of  the  word
       "mapping"  followed  by  a  pattern in shell glob syntax.  Each mapping
       stanza must contain a script definition.  The named script is run  with
       the  physical  interface  name as its argument and with the contents of
       all following "map" lines (without the leading  "map")  in  the  stanza
       provided to it on its standard input. The script must print a string on
       its       standard       output       before        exiting.        See
       /usr/share/doc/ifupdown/examples  for  examples of what the script must
       print.

       Mapping a name consists of searching the remaining mapping patterns and
       running the script corresponding to the first match; the script outputs
       the name to which the original is mapped.

       ifup  is  normally  given  a  physical  interface  name  as  its  first
       non-option  argument.   ifup also uses this name as the initial logical
       name for the interface unless it is accompanied by  a   suffix  of  the
       form  =LOGICAL,  in  which  case  ifup  chooses  LOGICAL as the initial
       logical name for the interface.  It then maps this name, possibly  more
       than  once  according  to  successive mapping specifications,  until no
       further mappings are possible.  If the resulting name is  the  name  of
       some  defined  logical  interface  then  ifup  attempts to bring up the
       physical interface as that logical  interface.   Otherwise  ifup  exits
       with an error.

       Stanzas defining logical interfaces start with a line consisting of the
       word "iface" followed by the name of the logical interface.  In  simple
       configurations  without  mapping stanzas this name should simply be the
       name of the physical interface to which it  is  to  be  applied.   (The
       default mapping script is, in effect, the echo command.)  The interface
       name is followed by the name of the address family that  the  interface
       uses.   This  will  be  "inet" for TCP/IP networking, but there is also
       some support for IPX networking ("ipx"), and IPv6 networking ("inet6").
       Following  that  is  the  name  of  the  method  used  to configure the
       interface.

       Additional options can be given on  subsequent  lines  in  the  stanza.
       Which  options  are  available  depends  on  the  family and method, as
       described below.  Additional options can be  made  available  by  other
       Debian   packages.   For  example,  the  wireless-tools  package  makes
       available a number of options prefixed with "wireless-"  which  can  be
       used  to  configure  the interface using iwconfig(8).  (See wireless(7)
       for details.)

       Options are usually indented for clarity (as in the example above)  but
       are not required to be.

VLAN AND BRIDGE INTERFACES

       To  ease  the  configuration  of  VLAN  interfaces, interfaces having .
       (full stop character) in the  name  are  configured  as  802.1q  tagged
       virtual  LAN  interface.  For  example,  interface  eth0.1 is a virtual
       interface having eth0 as physical link, with VLAN ID 1.

       For compatibility with bridge-utils package, if bridge_ports option  is
       specified, VLAN interface configuration is not performed.

IFACE OPTIONS

       The  following  "command"  options  are  available for every family and
       method.  Each of these options can be given multiple times in a  single
       stanza,  in  which case the commands are executed in the order in which
       they appear in the stanza.  (You can ensure a command  never  fails  by
       suffixing them with "|| true".)

       pre-up command
              Run  command  before bringing the interface up.  If this command
              fails then ifup aborts, refraining from marking the interface as
              configured,  prints  an  error message, and exits with status 0.
              This behavior may change in the future.

       up command

       post-up command
              Run command after bringing the interface up.   If  this  command
              fails then ifup aborts, refraining from marking the interface as
              configured (even though it has really been  configured),  prints
              an  error  message,  and exits with status 0.  This behavior may
              change in the future.

       down command

       pre-down command
              Run command before taking the interface down.  If  this  command
              fails  then  ifdown  aborts, marks the interface as deconfigured
              (even though it has not really  been  deconfigured),  and  exits
              with status 0.  This behavior may change in the future.

       post-down command
              Run  command  after  taking the interface down.  If this command
              fails then ifdown aborts, marks the interface  as  deconfigured,
              and  exits  with  status  0.   This  behavior  may change in the
              future.

       There exists for each  of  the  above  mentioned  options  a  directory
       /etc/network/if-<option>.d/  the  scripts  in  which  are  run (with no
       arguments)  using  run-parts(8)  after  the  option  itself  has   been
       processed.  Please  note  that  as post-up and pre-down are aliases, no
       files in the corresponding directories are processed.  Please  use  if-
       up.d and if-down.d directories instead.

       All  of  these  commands  have  access  to  the  following  environment
       variables.

       IFACE  physical name of the interface being processed

       LOGICAL
              logical name of the interface being processed

       ADDRFAM
              address family of the interface

       METHOD method of the interface (e.g., static)

       MODE   start if run from ifup, stop if run from ifdown

       PHASE  as per MODE, but with finer granularity, distinguishing the pre-
              up, post-up, pre-down and post-down phases.

       VERBOSITY
              indicates whether --verbose was used; set to 1 if so, 0 if not.

       PATH   the   command   search   path:  /usr/local/sbin:/usr/local/bin:
              /usr/sbin:/usr/bin:/sbin:/bin

       Additionally, all options given in an interface definition  stanza  are
       exported to the environment in upper case with "IF_" prepended and with
       hyphens  converted  to  underscores  and  non-alphanumeric   characters
       discarded.

       When  ifupdown  is  being  called  with  the --all option, before doing
       anything to interfaces, if calls all the hook scripts (pre-up or  down)
       with  IFACE set to "--all", LOGICAL set to the current value of --allow
       parameter  (or  "auto"   if   it's   not   set),   ADDRFAM="meta"   and
       METHOD="none".   After all the interfaces have been brought up or taken
       down, the appropriate scripts (up or post-down) are executed.

INET ADDRESS FAMILY

       This section documents  the  methods  available  in  the  inet  address
       family.

   The loopback Method
       This method may be used to define the IPv4 loopback interface.

       Options

              (No options)

   The static Method
       This  method  may be used to define Ethernet interfaces with statically
       allocated IPv4 addresses.

       Options

              address address
                     Address (dotted quad/netmask) required

              netmask mask
                     Netmask (dotted quad or CIDR)

              broadcast broadcast_address
                     Broadcast address (dotted quad, + or -).  Default  value:
                     "+"

              metric metric
                     Routing metric for default gateway (integer)

              gateway address
                     Default gateway (dotted quad)

              pointopoint address
                     Address  of  other  end  point  (dotted  quad).  Note the
                     spelling of "point-to".

              hwaddress address
                     Link local address.

              mtu size
                     MTU size

              scope  Address validity scope. Possible  values:  global,  link,
                     host

   The manual Method
       This method may be used to define interfaces for which no configuration
       is done by default. Such interfaces can be configured manually by means
       of up and down commands or /etc/network/if-*.d scripts.

       Options

              hwaddress address
                     Link local address.

              mtu size
                     MTU size

   The dhcp Method
       This  method  may be used to obtain an address via DHCP with any of the
       tools: dhclient, pump, udhcpc, dhcpcd. (They have been listed in  their
       order  of  precedence.) If you have a complicated DHCP setup you should
       note that some of these clients use their own configuration  files  and
       do not obtain their configuration information via ifup.

       Options

              hostname hostname
                     Hostname to be requested (pump, dhcpcd, udhcpc)

              metric metric
                     Metric for added routes (dhclient)

              leasehours leasehours
                     Preferred lease time in hours (pump)

              leasetime leasetime
                     Preferred lease time in seconds (dhcpcd)

              vendor vendor
                     Vendor class identifier (dhcpcd)

              client client
                     Client identifier (dhcpcd)

              hwaddress address
                     Hardware address.

   The bootp Method
       This method may be used to obtain an address via bootp.

       Options

              bootfile file
                     Tell the server to use file as the bootfile.

              server address
                     Use  the  IP  address  address  to  communicate  with the
                     server.

              hwaddr addr
                     Use addr as the hardware address instead of  whatever  it
                     really is.

   The tunnel Method
       This method is used to create GRE or IPIP tunnels. You need to have the
       ip binary from the iproute package. For GRE tunnels, you will  need  to
       load the ip_gre module and the ipip module for IPIP tunnels.

       Options

              address address
                     Local address (dotted quad) required

              mode type
                     Tunnel type (either GRE or IPIP) required

              endpoint address
                     Address of other tunnel endpoint required

              dstaddr address
                     Remote address (remote address inside tunnel)

              local address
                     Address of the local endpoint

              gateway address
                     Default gateway

              ttl time
                     TTL setting

              mtu size
                     MTU size

   The ppp Method
       This  method  uses  pon/poff  to  configure  a PPP interface. See those
       commands for details.

       Options

              provider name
                     Use name as the provider (from /etc/ppp/peers).

              unit number
                     Use number as the ppp unit number.

              options string
                     Pass string as additional options to pon.

   The wvdial Method
       This method uses wvdial to configure a PPP interface. See that  command
       for more details.

       Options

              provider name
                     Use name as the provider (from /etc/wvdial.conf).

   The ipv4ll Method
       This  method  uses avahi-autoipd to configure an interface with an IPv4
       Link-Layer address (169.254.0.0/16 family). This method is  also  known
       as  APIPA  or  IPAC,  and  often  colloquially referred to as "Zeroconf
       address".

       Options

              (No options)

IPX ADDRESS FAMILY

       This section documents the methods available in the ipx address family.

   The static Method
       This method may be used to setup an  IPX  interface.  It  requires  the
       ipx_interface command.

       Options

              frame type
                     type of Ethernet frames to use (e.g. 802.2)

              netnum id
                     Network number

   The dynamic Method
       This method may be used to setup an IPX interface dynamically.

       Options

              frame type
                     type of Ethernet frames to use (e.g. 802.2)

INET6 ADDRESS FAMILY

       This  section  documents  the  methods  available  in the inet6 address
       family.

   The auto Method
       This method  may  be  used  to  define  interfaces  with  automatically
       assigned IPv6 addresses. Using this method on its own doesn't mean that
       RDNSS options will be applied, too. To make this happen, rdnssd  daemon
       must be installed, properly configured and running. If stateless DHCPv6
       support is turned on, then additional network configuration  parameters
       such  as  DNS  and  NTP  servers  will be retrieved from a DHCP server.
       Please note that on ifdown, the lease  is  not  currently  released  (a
       known bug).

       Options

              privext int
                     Privacy extensions (RFC4941) (0=off, 1=assign, 2=prefer)

              accept_ra int
                     Accept     router     advertisements     (0=off,    1=on,
                     2=on+forwarding). Default value: "2"

              dhcp int
                     Use stateless DHCPv6 (0=off, 1=on)

   The loopback Method
       This method may be used to define the IPv6 loopback interface.

       Options

              (No options)

   The static Method
       This method may be used to define interfaces with  statically  assigned
       IPv6 addresses. By default, stateless autoconfiguration is disabled for
       this interface.

       Options

              address address
                     Address (colon delimited/netmask) required

              netmask mask
                     Netmask (number of bits, eg 64)

              gateway address
                     Default gateway (colon delimited)

              media type
                     Medium type, driver dependent

              hwaddress address
                     Hardware address

              mtu size
                     MTU size

              accept_ra int
                     Accept    router     advertisements     (0=off,     1=on,
                     2=on+forwarding)

              autoconf int
                     Perform   stateless   autoconfiguration   (0=off,  1=on).
                     Default value: "0"

              privext int
                     Privacy extensions (RFC3041) (0=off, 1=assign, 2=prefer)

              scope  Address validity scope. Possible  values:  global,  site,
                     link, host

              preferred-lifetime int
                     Time that address remains preferred

              dad-attempts
                     Number  of attempts to settle DAD (0 to disable). Default
                     value: "60"

              dad-interval
                     DAD state polling interval  in  seconds.  Default  value:
                     "0.1"

   The manual Method
       This method may be used to define interfaces for which no configuration
       is done by default. Such interfaces can be configured manually by means
       of up and down commands or /etc/network/if-*.d scripts.

       Options

              hwaddress address
                     Hardware address

              mtu size
                     MTU size

   The dhcp Method
       This  method  may be used to obtain network interface configuration via
       stateful DHCPv6 with dhclient. In stateful DHCPv6, the DHCP  server  is
       responsible for assigning addresses to clients.

       Options

              hwaddress address
                     Hardware address

              accept_ra int
                     Accept     router     advertisements     (0=off,    1=on,
                     2=on+forwarding). Default value: "1"

              autoconf int
                     Perform stateless autoconfiguration (0=off, 1=on)

   The v4tunnel Method
       This method may be used to setup an IPv6-over-IPv4 tunnel. It  requires
       the ip command from the iproute package.

       Options

              address address
                     Address (colon delimited) required

              netmask mask
                     Netmask (number of bits, eg 64)

              endpoint address
                     Address  of  other  tunnel  endpoint  (IPv4  dotted quad)
                     required

              local address
                     Address of the local endpoint (IPv4 dotted quad)

              gateway address
                     Default gateway (colon delimited)

              ttl time
                     TTL setting

              mtu size
                     MTU size

              preferred-lifetime int
                     Time that address remains preferred

   The 6to4 Method
       This method may be used to setup an 6to4 tunnel.  It  requires  the  ip
       command from the iproute package.

       Options

              local address
                     Address of the local endpoint (IPv4 dotted quad) required

              ttl time
                     TTL setting

              mtu size
                     MTU size

              preferred-lifetime int
                     Time that address remains preferred

CAN ADDRESS FAMILY

       This section documents the methods available in the can address family.

   The static Method
       This  method  may  be  used  to  setup an Controller Area Network (CAN)
       interface. It requires the the ip command from the iproute package.

       Options

              bitrate bitrate
                     bitrate (1..1000000) required

              samplepoint samplepoint
                     sample point (0.000..0.999)

              loopback loopback
                     loop back CAN Messages (on|off)

              listenonly listenonly
                     listen only mode (on|off)

              triple triple
                     activate triple sampling (on|off)

              oneshot oneshot
                     one shot mode (on|off)

              berr berr
                     activate berr reporting (on|off)

KNOWN BUGS/LIMITATIONS

       The ifup and ifdown programs work with so-called  "physical"  interface
       names.    These   names   are  assigned  to  hardware  by  the  kernel.
       Unfortunately it can happen that the kernel assigns different  physical
       interface  names  to the same hardware at different times; for example,
       what was called "eth0" last time you booted is now  called  "eth1"  and
       vice  versa.   This  creates  a  problem  if  you want to configure the
       interfaces appropriately.  A way to deal with this problem  is  to  use
       mapping  scripts  that  choose logical interface names according to the
       properties of  the  interface  hardware.   See  the  get-mac-address.sh
       script  in  the  examples  directory  for  an example of such a mapping
       script.  See also Debian bug #101728.

AUTHOR

       The    ifupdown    suite    was    written     by     Anthony     Towns
       <aj@azure.humbug.org.au>.   This  manpage  was contributed by Joey Hess
       <joey@kitenet.net>.

SEE ALSO

       ifup(8), ip(8), ifconfig(8), run-parts(8), resolvconf(8).

       For advice on configuring this package read the  Network  Configuration
       chapter    of    the    Debian    Reference    manual,   available   at
       http://www.debian.org/doc/manuals/debian-reference/ch05.en.html  or  in
       the debian-reference-en package.

       Examples   of   how   to   set   up   interfaces   can   be   found  in
       /usr/share/doc/ifupdown/examples/network-interfaces.gz.